1. Technical Field
The present invention relates to liquid ejecting apparatuses and raster line forming methods.
2. Related Art
Inkjet printers that carry out printing by ejecting a liquid (ink) onto various media such as paper, cloth, and film are well known as an example of liquid ejecting apparatuses. These printers are provided with a head in which a plurality of nozzles for ejecting liquid onto a medium are arranged in a first direction (sub-scanning direction), and this head ejects liquid while moving in a second direction (main scanning direction) that intersects the first direction (International Publication WO 01/03930).
From a viewpoint of increasing picture quality, the above-mentioned printer carries out so-called overlap printing, for example. That is, the printer alternately moves the head a plurality of times in the second direction and the first direction, and forms a single raster line by causing two or more different nozzles to eject liquid.
Incidentally, from a viewpoint of increasing the printing speed, some printers are provided with a head unit that has a plurality of the aforementioned heads arranged along the first direction. In this case it is conceivable that the width in the first direction of the head unit is made wider than the width in the first direction of the medium such that liquid is ejected at one time across an entire width of the medium, for example. However, with this configuration, in the case where a total amount of movement of the head unit in the first direction during printing is large, it is necessary to increase the width of the head unit in the first direction in order to have liquid ejected across the entire width of the medium at a single time during movement in the second direction.
Further, it is known that liquid ejecting characteristics vary due to individual differences of the heads. For example, one head has a characteristic of ejecting liquid easily, while another head has a characteristic of ejecting liquid with difficulty. For this reason, in the case where the plurality of heads that constitute the head unit ejects liquid, a so-called density irregularity or the like may occur due to differences in the ejection characteristics of each of the heads and as a result, there is a risk for image quality to deteriorate.